In general, an apparatus including a tiltable display unit, such for example as a notebook type personal computer (laptop computer), is unlikely to overturn even when the display unit is opened widely, because the apparatus has a light weight on the display unit side and a heavy weight on a keyboard side incorporating circuits and a battery.
In recent years, besides laptop computers, tablet computers have become popular in which circuits and a battery are incorporated into a display unit side equipped with a touch panel. Hereinafter, the display unit may be also referred to as a display.
No problems occur when such a tablet is used independently. However, in response to a demand that users can make input to a tablet through a keyboard, a thin keyboard connectable to the tablet has been marketed. When the tablet connected to the thin keyboard is used, the barycenter is on a display side because circuits and a battery are incorporated into the tablet (the display side), and therefore the tablet is likely to overturn when the display is opened and tilted.
To suppress occurrence of overturn of an apparatus which includes a display and is likely to overturn when the display is tilted, there are techniques of placing a weight on the keyboard or the stand, and mounting an overturn prevention plate of manual pull-out type.
In the stand of a thin display device, to prevent overturn of the thin display device on a stand, a technique of pulling out an auxiliary baseplate incorporated into a base section of the stand is disclosed in Japanese Laid-open Patent Publication No. 2000-47599.
However, the technique disclosed in Japanese Laid-open Patent Publication No. 2000-47599 has a problem with the operability since the auxiliary baseplate incorporated into the base section of the stand has to be pulled out by the user. To solve the foregoing problem, Japanese Laid-open Patent Publication No. 2004-133160 discloses a technique of automatically sliding and moving a part of the base section on the stand according to tilt of the image display unit so as to increase installation area of the stand.
The technique disclosed in Japanese Laid-open Patent Publication No. 2004-133160 converts rotary motion of a rotary shaft of the image display unit into linear motion via a gear, a cam, a link mechanism and so on, and when the image display unit is tilted, causes an auxiliary plate to protrude from the baseplate so as to suppress occurrence of overturn of the image display unit.
Japanese Laid-open Patent Publication No. 04-616 discloses a technique similar with the technique disclosed in Japanese Laid-open Patent Publication No. 2000-47599, In this technique, an information processing apparatus including a display is provided with a stabilizer provided on the rear side thereof, and is stabilized by pulling out the stabilizer from the inside of the apparatus.
Further, Japanese Laid-open Patent Publication No. 09-292931 discloses a technique of suppressing occurrence of overturn of an information processing apparatus including an LCD panel. Specifically, a first gear is provided on a rotary shaft of the LCD panel, and when the LCD panel is tilted, rotation of the first gear is transmitted to a rack via a second gear, and the rack is caused to protrude behind the rear of the apparatus so as to suppress occurrence of overturn of the apparatus.
However, the techniques disclosed in Japanese Laid-open Patent Publication Nos. 2000-47599 and 04-616 have a problem that operation is complicated since the auxiliary plate and the stabilizer are pulled out manually. The techniques disclosed in Japanese Laid-open Patent Publication Nos. 2004-133160 and 09-292931 have a problem that the overturn prevention mechanisms are large in size because the protrusion length of the auxiliary plate or the rack is determined by the number of teeth of the gear, and the mechanism has to have a gear with a large diameter to secure the protrusion length of the auxiliary plate or the rack.
According to an aspect of the embodiment, it is an object of the present application to provide an overturn prevention device for an apparatus including a tiltable housing, equipped with an overturn prevention mechanism achieving downsizing by causing an overturn prevention piece to protrude by utilizing rotation of a rotary shaft configured to tilt the housing including a display.